Doctor of Philosophy (PhD)


Nutrition and Food Sciences

Document Type



Consumers are currently more conscious about salt and sugar intake than they were in the past. Visual cues have been shown to impact consumers’ cognitive and their taste perceptions. Current research information about visual cues enhancing human’s tastes expectation of saltiness and sweetness is limited. The sophisticated sensory analysis for products containing a reduced amount of salt and sugar is undoubtedly time–consuming and costly if the sensory experiment is designed with many samples. Therefore, the following three studies were achieved: I) an examination of how intrinsic and extrinsic visual cues affect the overall consumer eating experiences; II) a comparison of non–sensory discrimination ability of R–Index (RIX) and Partial Projective Mapping (PPM) in the application of salt substitute; and III) a study of consumers’ responses to visual cues enhancing taste perceptions of saltiness and sweetness. In study I, 150 consumers visually evaluated their liking, emotion and purchase intent of ready–to–eat (RTE) salad with four different visual effects (green color, size, multicolor and package) that were nested in a given condition with or without product name. The visual factors strongly impacted consumer liking, emotion, and purchase intent. The color cues were more sensitive for distinguishing consumers liking score and emotion while the purchase intent was dependent on how well consumers liked and felt about the product, not just their liking alone. Study II compared RIX and PPM for discrimination ability of salt substitutes containing KCl and L–Arginine (bitterness blocker). The R–Index by the ranking method was used to determine sensory discrimination. Panelists ranked three salt mixture concentrations (0.5%w/v, 1% w/v and 1.5%w/v) for saltiness and bitterness intensity; hence they participated 6 RIX sessions (2 attributes x 3 concentrations). In contrast, PPM allowed panelists to evaluate all samples simultaneously. Both RIX and PPM performed similarly for sensory discrimination with slight differences; however, PPM took a shorter time to complete the task and may offer slightly more sensitivity to differences. Study III, the effect of visual cues on taste expectation was divided into two parts; visual expectation of saltiness perception using chicken broth as a food model, and expectation of sweetness expectation using syrup which was added to brewed coffee. Color cue strongly influenced consumers’ eating behavior by affecting their taste expectation during the decision–making process, and this finding may alleviate overconsumption of salt and sugar.



Committee Chair

Prinyawiwatkul, Witoon